Invalid characters can be output but will result with corrupted file
Created originally on Bitbucket by Ying-Jui Chen
Some characters cause corrupted xlsx file. I'm not sure what characters will cause the corrupted file.(I'm sure at least \x11 will.)
So I did a replace before set the value. for i in xrange(0, 32): ok_str = ok_str.replace(chr(i), '?')
I'm thinking it will be better if the library do this.